The owners of 60,000 cargo ships are bracing for tighter emissions rules that are forcing them to make a multibillion-dollar choice: Start buying cleaner-burning fuel or invest in a device that treats the ship’s exhaust before letting it out. It isn’t an easy call. Retrofitting a vessel with a sulfur-trapping exhaust system called a “scrubber” costs as much as $10 million a ship, while cleaner fuels are about 55% more expensive than the ones shipping operators use now. Whether it makes sense to install scrubbers and absorb a bigger financial hit upfront depends on whether scrubbers will be adequate to meet even stricter pollution caps expected in the future and the availability and cost of cleaner fuels. Both factors are difficult to gauge. Scrubbers involve “a complicated and expensive installation of $5 to $10 million per ship and the benefit to the environment is still not clear,” said Soren […]